Combined grizzly and ball mill



Jan. 1, 1929. l 1,697,531 A. F. LEVITT COMBNED GRIZZLY AND BALL MILL Filed July 11, 1927 2 Sheets-Sheet l 'l F\G\. 'L

to mvpNToR QRTHUQ F. LEV \TT Jan.`1, 1929.

A. F. LEVITT COMBINED GRIZZLY AND BALL MILL Filed July. 11, 1927 Mii@ Patented Jan. 1, 1929.

ARTHUR F. LEVITT, OF LOS ANGELESyC-ALIFOBNIA.

COMBINED GRIzzLY Aim BALI.. MILL.

Application led Julyv 11,

vcarried around in the rotation of the drum byy the said grizzly bars, hence operating in a ball mill manner'onth'e material leing ground.

' Another objectof my invention is in allowing passage of aggregates between the grizzly bars into the portions of the mill having the balls, where it'is acted on by the balls y l5 and on the elevation of the balls through the rolling ofthe drum, the fine aggregate is dumped through the grizzly bars and allowed to sift through screens into a discharge spout. In construct-ing my invention I utilize a drum of large diameter and of comparatively lshort length in an axial direction. This drum. has annular tracks thereon suppoiyted on rollers, at least one of which may be employed to drive the drum. Inside the drum and extending lengthwise thereof between the heads, there are a plurality of crossing rows of bars forming a segmentalgrizzly arrangement internally of the drum. There are balls of different sizes in each' of -these segmental parts. The aggregate is fed into the drum at about its centerand after passing through the various grinding operations due to the rotation of the drums, itis discharged through screens installed in the segmental parts.

My invention is illustrated in the accompanying drawings, in which:

Figure 1 is a vertical longitudinal section of my mill taken on the line 1-1 of Fig.. 2 in the direction of the arrows. 7 i Figure 2 is a vertical transverse section' taken on of the arrows. Figure taken in the direction of the arrow 3 of Fig. 2.

Figure 4 is an end elevation of the mill. Figure- 5 is a: vertical section thro'ugh a combined mill and amalgamator.

FigureG is a side elevation partly'broken away of a construction of Fig. 5.

Figure 7 is a detail section on the-line 7--7 of Fig. 5 showing the manner of mounting the amalgamatr plates.

Figure 8 is a partial vertical sectionl through another type of combined mill and 525 .il.111i1lganaator,b y l line 2-2 ofFig 1 in the direction 3 is a side elevation of the drum' balls roll on other and on the grizzly bars, and moreover 10,5

1927. serial No. 14,855.

Figure 9 is an edge view of a. mill used for drying, burning or calcining material.l

In constructing the drum this has a c lindrical structure 11 to which `are secure annular angles 12 on `the inside andto theinner flange 13 of these a-nglesthere is'secured a vback plate J14,-this being a large disk, and 'a front plate15, also a disk. `The front plate has an infeeding openingl preferably circular. A plurality o'ftracks 17 which lare annular are secured to the outside of the cylindrical part 11 of the drum. In the illus- Y tration shown, one of these tracks is formed as a large gear with teeth 18.v 4The drum is supported on rollers 19 journaled in a suitable'manner and supported on a suitable base 20. At least one of these rollers is constructed as a. pinion 21, mounted on a rotatable shaft- 22 and driven from the pulleyr23, thus rotating the drum. y u' Internally of the drum there are rows 24 and 25 of bars vsimilar to bolts, which extend longitudinally of the drum, that is, between the plates 14 and 15. These rows are preferably" arranged at right angles, one to the other, and are illustrated as being substantially tangential to theV circle forming the opening 16'. Thus theserows otl barsA form grizzlies', and, with the inside of the cylinder 11, form segmental grinding chambers 26. l

At certain parts of the' periphery of Ithe drum 11 there are screen bars 27 with spaces 28 therebetween, these bars extending around part of each segmental grinding chamber 26. Secured to the outside of the cylinder 11 there are brackets 29 which hold a foraminated screen 30 in posit-ion. These screens may be of any` desired mesh and are designed to be insertable and removable sothat the material ymay be ground to the desired size. Mill balls 31 are located in each of the grinding segments 26. In the illustration shown the balls in the diferent segments are of different sizes, although this is optional.v They are maintained as separateunits, confined in position vby thedrum 11 and the' -rows 24 and 25 of the bars forming the grizzly. I-Iencewhen a drum rotates, the

the inside of the drum on each theI balls are carried up .above the horizontal diameter of the drum and drop downwardly, giving a. certain impact. l v v The aggregate is'fed into the drum through the feed spout 32 andiis d' Charged through 11.19A

' suitable for the small aggregate. Practically immediately after the material is ground small enough to pass through the discharge a discharge chute 33 which has lateral lextension chutes 34 carried partly circumferen- -tially around the drum and up to substantially the horizontal diameter. The chute discharges into a discharge pipe 35.

The manner of operation of my combined ball mill with the grizzlies is substantially as follows:

As the aggregate is'dropped into the drum it may pass int-o the small chambers 36 between the parallel rows of grizzly bars, or it may strike these bars, passing therethrough, depending on the spacing of the bars and the position of the drum in its rotation. As the aggregate is free Ato pass through the bars it finds its way into the segments having the ballsand-there it is subjected lto a grinding action. The balls roll one on the other and on the aggregate and are also lifted above the horizontal, dropping with a certain impact against the aggregate.

I. find it advisable to space the grizzly bars different distances apart, making segments with screen grizzlies, allowing different size aggregate to enter into such grinding seg? ments.v The balls in said segments are also graduated in size in accordance with the size of the aggregate, so that the fine material will readily fall out ofthe segments designed for the large aggregate and enter the segments screens 30, it finds its way clear through into the discharge chutes; hence material which is ground sufficiently fine isnot worked over yand over again. but the action of the mill is practically confined tov dealing with aggregates larger than the product.

From the above description vit can be seen that I have developed a simple type of ball mill in which the grizzlies enter as an essential element in the grinding and these grizzlies function to screen the material in the mill.- I have, therefore, not only made an invention in the mill itself, but in the method `of grinding. Y

For some types of work Ifind itadvisable to have openings 4() in the back plate, these openings being preferably made in the shape shown in Fig. 3 and are op osite the side of each of the' grinding cham ers 26. Screens 41 are secured at these openings by any suitable framing. Outside of the openings there 1s a flared collar 42 securedto the plate 14 and partly surrounding lthe lower edge of this collar there is a lateral discharge chute 43 (note particularlyFigsB and 4).

I also, in some cases, have a water pipe 44 dlscharging water into the feed spout 32 in orfllier to wash material passing through my m1 In order to block any of the screens I provide a series of bent plates 45, illustrated in Fig. 1, which are secured b v screws ont-he like to the periphery ofthe drum 11 over the screens 30. This prevents outlet of material at such screens and forces it out through the screens 40. I may utilize one or more of these plates so that when washing material by injecting water, the light slime may be floated out of the side screens 41 and discharge by the lateral discharge chute 43.

Then again, for ordinary grinding in which the product is to be discharged through the `screensf30, I may attach side plates 46 of material I place a row of bars 47 between the heads 14 and 15. of the drum and adjacent the cylindrical wall 11 and between the rows of bars 24 and 25. Thus the balls by being confined to the four segments shown are kept out of contact with t-he periphery of the drum and material which is too coarse to pass through the screens settles between Athis peripheral row of grizzly bars, and the inside of the drum adjacent the screens.

In the 4combine-d mill and amalgamator as illustrated in Figs. 5 and 6, I utilize somewhat the same type of drum, this having an outer shell 50 with heads 51 and 52, and across the heads I provide rows of bars 53, 54 and 55, forming grizzlies. The bars 54 and 55 are preferably arranged at right angles to each other and parallel to diameters of the drum. The curved row55'is concentric to the'outer shell of the drum. Balls 56 4are inserted in the various segments, and material is fed into the drumthrough an opening 57 in one of the heads, through a charging chute 58,

. there being a water supply pipe 58 adjacent thereto. The drum is provided with a number of openings 59 in the shell and these have screens 60 fitted thereover. The screens are preferably secured to the shell 50 by a hinge 61 at one end, and by a lock 62 at the other end, this lock being controlled by a key.

Internally of the drum and spaced between the row 55 of grizzly bars and the periphery of the drum there are' a plurality of amalgamating plates 63, such plates having perforations 64 therethrough; the plates are re- Amovable and are secured in slotted lugs 65 on the opposite heads 51y and 52 of the drum, and may be secured in place by set screws 66,

or other suitable clamping means. ,It will be noted that there are provided inner and outer rows of these plates, the plates preferably being--flat andstaggered, one-inv relation tqthc lao -gamate is formedl on the plates.

chambers.

The drum has peripheral tracks 67 sup'- l ported .on rollers 68 mounted on a suitable frame 69, one or more of which may be driven in any suitable manner. The crushed prod-l uct of the mill is discharged into a collecting chute 7.0 and discharged through a hopper 71.

In-t-he construction shown in Fig. 8 the. arrangement of grizzly bars is s iibstantially the saine as that set forth in connection with Figs. 5 and 6, but in this case the amalgamating plates 7 2 are substantially radial and are provided with apertures 73 therethrough. `In addition there are plate-holding lugs 74 positioned directly outside of the cylindrical row of grizzly bars 55. The outside screens are of the same construction as set forth in Figs. 5 and 6l and may be open.

Thevmanner of operation and functioning of my combined mill and amalgamator as shown in Figs. 5 through 7 is as follows:

The material to be crushed is`fed into the mill,as above described, and a certain amount of mercury is also charged in the mill, this Ybeing in proportion to the metal that it is desired to amalgamate', the amount required for gold being proportionate to the assay of the 'orefbeing crushed, .or the deposit being workedzfln the continued rotation ofthe drum the ore is crushed by the balls and grizzlies and if placer deposits arebeing Worked, the material is ground and worked over; becomingin a fine disintegrated condition,\so

that the free gold may contact with the amal.

ga-matin plates 63which are suitably plated, preferab y on both sides,and on account of the mercury mixing in' `with the ore an amal- The tailings pass through the screens. After a suitable run, and when it appears that the plates require cleaning, the screens 60 may be opened and the plates removed and scraped.

When my mill is used for working placer. deposits where quartz gold may be present, the crushing of the quartz by the balls and grizzlies separates the free old I and the placer gold,-where nuggets m y' be present. This, together with the washingoperation by\ an influx of water, separates the free gold, which is Washed through the grizzlies and collects on the screens; also, the iat placer` gold separates from the aggregate and 'likewise collects on the screens. rlhis gold is then in good condition for amalgamation and, as

the grizziles protect thisfgold from aga-in.l

coming in contact with, the balls, it is left intactin its original condition for amalgamation treatment. The mill is then periodically cleaned and the free gold collected off the screens. rlhe rows of grizzly bars co-ncentric to the outer shell of the drum prevent the gold from being're-ground or pulverized linthe operationof the mill, as frequently hap ens iii-ordinary milling operations. v The ,tailings are then lfree to take over the ordinary course through the screens, and any iron sufficiently valuable, in other words carrying gold, may be concentrated and worked in theordinary way.

In the construction shown in Fig. 9 the drum may be'substantially similar to that shown in Figs. 1 through Ll, it being preferable, however, to omit the screens on the side. As this type may be utilized for drying, burning or calciiiing the product, a fuel pipe 8O has a nozzle extending into the drum through one of its heads. The flame causes the .grizzly bars and the balls to'becoine very hot, therefore, as the material is being worked and ground it frbecomes thoroughly dried,

the moisture escaping upwardly through yt-he screens, andthe dry product discharged through the bottom screens.v The same pro.-

cedure is followed in more intense heating,

such as for burning or calcining a, product,

as in treatingkieselguhr.

A characteristic vfeature of my milldis that it is self-cleansing, the fine material, by the action of the mill, is cleared from the grizzly bars andfrom the crushing apparatus. Moreover, asithe fines readily ass through the grizzlies and they are not su jected to regrinding, there is`no-sliming of the ore, as when once .ground and suiiciently fine the material is vnot subjected to. any further grinding.

l find it advantageous to have grizzly bars 47a positioned adjacent the shell of the drum at'the outer ends of the smallchambers 36, as shown in Fig. l, and to have fairly. large balls 31a forifilling in such chambers. the rotation of the drum these balls are free to roll from' one chamber to another, rolling on the lowermost of the parallel rows Aof grizzly bars 24. This gives a pulverizing action tothe material immediately it has been fed into the drum by the feed spout 32;

In the construction of Figs. 5 through 8 the bars at the extremities of these small chambers are designated 55a and the bals operating in such chambers as 56a, the acti n beingthe same as described above, and in addition, these grizzly bars prevent the balls and the material immediately on being fed in coming inl contact with the amalgama-ting plates. Y

Various ,changes mayl be made in the principles of my invention without departing from, the spirit thereof,l as set forth in the iie drum adapted in rotation ofthe drum to roll againstA the/ transverse bars and against the peripheral bars, and means to feed material'- to thefdrum and discharge the ground material therefrom. i

2. A mill comprising in combination a rotary drum having a plurality of sets of bars extending-lengthwise of the drum and spaced from the walls of the drum, balls disposed within the drum and adapted to encounter the bars upon rotation of the drum, and means to feed material into the drum and discharge the Crushed product.

3. A mill comprising'a drum, aiplurality of sets of bars extending lengthwise therein,

y said bars being arranged to separate different segments of the circumference of the drum, balls retained in said segmental sections by the bars of each set, and means to feed material to the drum and discharge the p crushed product.

4. A mill comprising a rotatable druml having a plurality of sets of bars extending lengthwise therein, said bars of each set being arranged to separate segments of the drum, balls located in each of said segments, the

periphery of the drum having openings at each ofthe segments to discharge the lcrushed product, and means to feed the material for crushing into the drum.

5. A mill comprising, a rotatable drum hav- A ing heads on opposite sides, a plurality of sets of bars, each set being arranged to separate a segmental section of the drum, each segmental section having openings in the periphery 'of the drum with screens at; such openings, balls in each ofthe segment-al sections and retained therein by the said bars of each section, means to feed material for grinding 'through one of the heads into the center of the drum, and means to collect the crushed product discharged through the screens.

6. A mill comprising in combination a drum having a cylindrical periphery with heads connecting the peripheral part of the drum, a plurality of sets of barsconnecting the heads, said sets each having two rows with a substantially right angular corner, the corner being near the center part' of the drum, the sets of bars and the section of the periphery of the drum separated by the rows ofbars forming segmental grinding cham bers, the periphery of the drum at the segmental -grinding chambers having openings f? with screens adjacent thereto, sets of balls in eachof these segmental grinding chambers, retained therein by the bars andthe periph- .eral part of th'e drum forming eachof such chambers, one of the heads `having a central opening to receivematerial for grinding,and

a series of openings with screens, and means to discharge material Apassing through the screens.

8. Ami ll comprising-a rotatable drum having heads on oppositesides and a peripheral section, a plurality of sets of bars extending between said heads, said bars being arranged to form segmental grinding chambers inthe drum, balls in said chambers, the peripher of the drum having a series of openings with screens, one of the sides of the drum having openings with screens, means-to feed material into the center of the drum from one side; and means to discharge material passing through the screens at the side and through the screens in the periphery of the drum.

9. A mill comprising in combination a rotatable drum having a peripheral shell connected byopposite heads, aplurality of rows of bars forming sets connected lengthwise of the drum between said heads, forming grizzlies, one row of bars being concentric lto the shell, and connectingrows of bars extending inwardly therefrom forming se mental grinding chambers, and -balls in said chambers.

10. A mill comprising in combination a 4 peripheralshell having opposite head plates, a plurality of sets 0f bars connected lengthwise of thedrum to said heads, said bars .forming grizzles, the bars being arranged to form segmental grinding chambers with a row of bars concentric to the shell, and lateral rows-of bars extending from the concentric row inwardly, ballsf" in said grinding chambers, the shell having openings therethrough with screens at the openings.

11. A mill, as claimed in claim 10, one of the heads having openingswith screens, the

screens being positioned opposite the grinding chambers. l

12. A mill comprising in combination a drum having'a peripheral shell connected by head plates, a plurality of sets of bars connecting the heads, one set'of bars being concentric to the shell, other sets extending 1nwardly therefrom and forming segmental grinding chambers with balls therein, a.l series of amalgamating plates positioned in the drum between the shell and the concentric row of bars, means to feed material `into theshell and to discharge the crushed product.

13.- A mill comprising in combination a peripheral shell connected by plates forming heads, a plurality of rows of bars connecting said heads, said bars being arranged to form segmental grinding chambers with a series of bars concentric to the shell and rows 'of barsextending inwardly therefrom towards the center of the shell, there being sets of ballsin each grinding chamber, a plurality of amalgamating plates positioned outside of the concentric rowl of bars and inside of the shell, the shell having a series of openings with screens at such openings, means to feed being removably connected to the heads.

n15. A mill comprising in combination a shell having opposite heads connected thereto, a series of setsof grizzlvdbars connecting llengthwise of the drum the heads arranged to 4form, segmental grinding chambers with balls 'I therein, means to feed material into the drum, means to dischar e hot gases into the drum,

and openings int e drum having screens.

16. The method of grinding comprising A feeding coarse material into a drum having a plurality of grinding chambers, each arranged with longitudinal bars spaced transversely and`circumferentially and balls retained by said bars in the grinding chambers, the material passing through'the bars and being operated on b .the balls, and being disl grndin chambers,

charged downwar y-throngh screens.

17. The method of grinding and amalgamating. comprising .introducing material #to be treated into a rotating drum, crushing and grinding the material in a pluralityl of each having sets of bars with ba s retained therein, the material being round by the balls and by contactwith the ars, the fine material dropping through the 'bars and passing over amalgamating plates carried by the drum.. A 18.Th'e method of grinding and amal- .gamating comprising introducing a material to' be-treated into a rotating drum,v grinding l the material 'in a plurality'of grinding chambers, each havlng an enclosure of; bars spaced a'. rt with balls retained therein, the

materialing ground by the balls vandpassing throu h the bars, and after grinding, the l 719. The method of grinding and heating l material comprising introducing a material to be treated into a rotating drum, grinding 50 the material in grinding chambers formed by 0 sets'of longitudinal ba-rs spaced transversely and circumferentially with' balls retainedim positionl by the bars, the material passing between the bars and being ground by the balls, Vdischarging heating gases -into the drum and allowing the ground product to discharge through screens in the periphery of the drum.

20. A-mill comprising in combination aj drum having a peripheral shell with heads at opposite sides of the shell, a row of grizzly bars connecting lengthwise of the drum between the heads and positioned concentric to the shell, a plurality of sets of'other grizzly vbars connected lengthwise of the drumhetween theheads, somel of which extend in- Jwardly from the said concentric row of bars towards the center of the drum and form` segmental grinding chambers with smaller grinding "chambers between J.the segmentalA A chambers, each of" said chambers having 'grinding balls therein, the grinding balls 1n the smaller chambers being lfree to,pass from one chamber to another but lthe balls in the segmental chambers being `retained therein, means to feed material in'to the drum and dis' l chargematerial from the drum, and means to rotate the drum. Y

In testimony whereof I have signed my name to this specification. A

ARTHUR n.' LEVITT. 

